Ritalin

SIDE EFFECTS

Nervousness and insomnia are the most common adverse
reactions but are usually controlled by reducing dosage and omitting the drug
in the afternoon or evening. Other reactions include hypersensitivity
(including skin rash, urticaria, fever, arthralgia, exfoliative dermatitis,
erythema multiforme with histopathological findings of necrotizing vasculitis,
and thrombocytopenic purpura); anorexia; nausea; dizziness; palpitations;
headache; dyskinesia; drowsiness; blood pressure and pulse changes, both up and
down; tachycardia; angina; cardiac arrhythmia; abdominal pain; weight loss
during prolonged therapy. There have been rare reports of Tourette's syndrome.
Toxic psychosis has been reported. Although a definite causal relationship has
not been established, the following have been reported in patients taking this
drug: instances of abnormal liver function, ranging from transaminase elevation
to hepatic coma; isolated cases of cerebral arteritis and/or occlusion;
leukopenia and/or anemia; transient depressed mood; aggressive behavior; a few
instances of scalp hair loss. Very rare reports of neuroleptic malignant
syndrome (NMS) have been received, and, in most of these, patients were
concurrently receiving therapies associated with NMS. In a single report, a
ten-year-old boy who had been taking methylphenidate for approximately 18
months experienced an NMS-like event within 45 minutes of ingesting his first
dose of venlafaxine. It is uncertain whether this case represented a drug-drug
interaction, a response to either drug alone, or some other cause.

In children, loss of appetite, abdominal pain, weight
loss during prolonged therapy, insomnia, and tachycardia may occur more
frequently; however, any of the other adverse reactions listed above may also
occur.

DRUG INTERACTIONS

Ritalin should not be used in patients being treated
(currently or within the proceeding two weeks) with MAO Inhibitors (see CONTRAINDICATIONS,
Monoamine Oxidase Inhibitors). Because of possible effects on blood
pressure, Ritalin should be used cautiously with pressor agents.

Methylphenidate may decrease the effectiveness of drugs
used to treat hypertension. Methylphenidate is metabolized primarily to
ritalinic acid by de-esterification and not through oxidative pathways.

Human pharmacologic studies have shown that racemic
methylphenidate may inhibit the metabolism of coumarin anticoagulants,
anticonvulsants (e.g., phenobarbital, phenytoin, primidone), and tricyclic
drugs (e.g., imipramine, clomipramine, desipramine). Downward dose adjustments
of these drugs may be required when given concomitantly with methylphenidate.
It may be necessary to adjust the dosage and monitor plasma drug concentration
(or, in case of coumarin, coagulation times), when initiating or discontinuing
methylphenidate.

Last reviewed on RxList: 8/1/2013
This monograph has been modified to include the generic and brand name in many instances.